The Nemo Sonic 0 Degree Down Sleeping bag is unmatched when it comes to warmth retention and finessing. Made with 100% recycled, bluesign approved materials, it boasts the secondgeneration of our flagship Thermo Gill vents, now with two adjustment stages for even more personalized temperature-setting. With a Toester footbox and 800 FP RDS-certified, hydrophobic down, Sonic is fine-tuned for frigid weather. Updated design with a multistage zipper system allows for an even wider temperature range and finetuned heat regulation. New chevron baffle construction better compartmentalizes down for more uniform loft and to eliminate insulation migration. Updated design incorporates sustainable materials throughout 100% recycled, bluesign approved fabric and 100% 800 FP RDS-certified, hydrophobic down. Keeps your feet warmer, protects against tent wall condensation, and protects down from moisture while drying damp clothes in the footbox 800 FP hydrophobic, PFC-Free